An alleged attack on a female staff member at a Department of Youth Services facility by accused teen murderer Philip Chism bears a chilling resemblance to the murder of a Danvers High School teacher, sources told Team 5 Investigates Karen Anderson.

Surveillance video captured Chism following the DYS employee into a locker room carrying an object that appeared to be a pencil.

He then allegedly began choking her, and as she started to scream he began to punch her, Anderson reported.

According to Anderson's report, within seconds staff members rushed in to help her and were able to quickly pull Chism off.

Authorities said Chism, then 14, killed Danvers teacher Colleen Ritzer, 24, with a box cutter he had taken to school after she asked him to stay after for help. He allegedly followed her into the school bathroom, where she was murdered and raped.

Chism has pleaded not guilty to charges of rape, robbery and murder.

"The Department of Youth Services is working closely with law enforcement to investigate an assault that took place on a member of the staff at our Dorchester facility," said Alec Loftus, DYS spokesman, declining for privacy reasons to identify Chism.

Chism was taken to Boston Medical Center for a mental health evaluation.